CVE-2025-66481
Summary
CVE-2025-66481 is a critical severity Cross-Site Scripting (XSS) vulnerability affecting thinkinai deepchat versions 0.5.1 and below. The vulnerability stems from insufficient sanitization of Mermaid content, allowing attackers to bypass existing security patches and potentially achieve Remote Code Execution (RCE) on a victim's machine.
Technical Details
CVE-2025-66481 describes a persistent XSS vulnerability within the DeepChat application, specifically related to the rendering of Mermaid diagrams. While a security patch was implemented for MermaidArtifact.vue, it proves insufficient due to the ability to bypass the sanitization using unquoted HTML attributes combined with HTML entity encoding. This allows malicious JavaScript code to be injected into the Mermaid diagram and subsequently executed within the context of the user's browser.
The vulnerability is further exacerbated by the application's use of electron.ipcRenderer. Attackers can leverage the XSS vulnerability to inject code that interacts with this interface, potentially leading to Remote Code Execution (RCE) on the victim's machine. The regex filter intended to strip dangerous attributes from the Mermaid content is ineffective against the described bypass techniques.
The attack flow involves an attacker injecting malicious Mermaid code into a DeepChat message or artifact. When a user views the content containing the malicious Mermaid diagram, the injected JavaScript code is executed, potentially allowing the attacker to steal sensitive information, modify the application's behavior, or even execute arbitrary code on the user's system.
Affected Products and Versions
- thinkinai deepchat versions 0.5.1 and below
Impact Assessment
Successful exploitation of CVE-2025-66481 can have severe consequences.
- Remote Code Execution (RCE): Attackers can potentially execute arbitrary code on the victim's machine through the
electron.ipcRendererinterface. - Data Theft: Sensitive information, such as user credentials, API keys, or chat logs, can be stolen.
- Application Manipulation: The attacker can modify the application's behavior, potentially leading to further compromise.
- Account Takeover: An attacker could potentially gain control of a user's DeepChat account.
Remediation
Immediate Actions
- Disable Mermaid Rendering: As a temporary workaround, consider disabling the rendering of Mermaid diagrams within DeepChat. This will prevent the exploitation of the vulnerability but will also limit the functionality of the application.
- Monitor Network Traffic: Monitor network traffic for suspicious activity that may indicate exploitation attempts.
Long-term Solutions
- Implement Robust Input Sanitization: The long-term solution involves implementing robust input sanitization for all user-supplied data, especially when rendering Mermaid diagrams. This should include strict validation and encoding of HTML attributes to prevent XSS attacks.
- Secure electron.ipcRenderer Interface: Review and secure the
electron.ipcRendererinterface to prevent unauthorized access and code execution. - Update Dependencies: Ensure that all dependencies, including the Mermaid library, are up-to-date with the latest security patches.
References
Detection & Scanning
Detecting CVE-2025-66481 requires careful inspection of DeepChat's Mermaid rendering functionality. Look for instances where user-supplied data is used to generate Mermaid diagrams without proper sanitization. Pay close attention to HTML attributes within the Mermaid code, as these are potential injection points.
Scan Your Website
Secably AI Scanner can detect this and 50+ other vulnerabilities automatically.
Start Free ScanScan Your Website for Vulnerabilities
Discover security issues before attackers do. Our AI-powered scanner checks for the vulnerabilities discussed in this guide and more.
Start Free Scan